Easy tips to quieten a two stroke

Wandell
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Wandell
Edited Date/Time 3/22/2014 8:26am
I am trying to make a 2002 CR125 and a 2011 YZ125 quieter. Both have Pro Circuit pipes with OEM silencers. Both were formally equipped with Pro Circuit shorty 304 silencers, but I replaced these because they were extremely loud. I've read that you can place a 12 to 18 inch section of a tire innertube over the silencer (letting the end dangle) and it will quieten the exhaust down. I've also read that putting a section of radiator or heater hose over the stinger will quieten the exhaust. Has anyone tried this or any other tips? I've tried to find a sound clip of the innertube trick but can't find one.
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rallendude
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rallendude 3/20/2014 10:49am
3/20/2014 10:49am
Buy a quiet exhaust. Turbine core or similar. If you could graft a KTM WXC silencer on them that would work.
Wandell
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Wandell 3/20/2014 7:32pm
3/20/2014 7:32pm
Yep, first thing I did was repack the OEM silencers and install them. I've been reading a lot about lining the airbox with foam. Will that really cut down the noise a noticeable amount?
Xnationalwrench, I know you have a lot of knowledge about MX bikes. What I'm looking for is something that will make a noticeable difference in the decibel level, even if it cost me a couple horsepower. Something along the lines of what the DB Dawg used to do for four strokes.

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b8res
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b8res 3/20/2014 10:04pm
3/20/2014 10:04pm
Wandell wrote:
I am trying to make a 2002 CR125 and a 2011 YZ125 quieter. Both have Pro Circuit pipes with OEM silencers. Both were formally equipped with...
I am trying to make a 2002 CR125 and a 2011 YZ125 quieter. Both have Pro Circuit pipes with OEM silencers. Both were formally equipped with Pro Circuit shorty 304 silencers, but I replaced these because they were extremely loud. I've read that you can place a 12 to 18 inch section of a tire innertube over the silencer (letting the end dangle) and it will quieten the exhaust down. I've also read that putting a section of radiator or heater hose over the stinger will quieten the exhaust. Has anyone tried this or any other tips? I've tried to find a sound clip of the innertube trick but can't find one.
I'm using a Leo Vince X3 silencer on my 05 YZ 125. It also come with a USFS approved screen spark arrestor as well. The screen can be removed really quick.
The X3 meets or exceeds USFS sound requirements. I race hare scrambles and our bikes get sound check on a routine basis.
The X3 is as quite or quieter than my FMF Turbine CoreII that is on my GasGas EC 200.
The X3 is on par with regards to size as the OEM silencer.
TRON
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TRON 3/21/2014 4:14am
3/21/2014 4:14am
Wandell wrote:
Yep, first thing I did was repack the OEM silencers and install them. I've been reading a lot about lining the airbox with foam. Will that...
Yep, first thing I did was repack the OEM silencers and install them. I've been reading a lot about lining the airbox with foam. Will that really cut down the noise a noticeable amount?
Xnationalwrench, I know you have a lot of knowledge about MX bikes. What I'm looking for is something that will make a noticeable difference in the decibel level, even if it cost me a couple horsepower. Something along the lines of what the DB Dawg used to do for four strokes.
I've been trying to talk Dan at Think Technology into making a sound foam kit for YZs for a couple months now. If you call him and want one, maybe he will hurry up and make a kit. Most of the pros are using his sound foam to pass sound check.
markit
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markit 3/21/2014 10:55am
3/21/2014 10:55am
Luck mine came with a hockey stick, what will help a little is to find a copper 90% that will fit into the end or your muff it'll take it down a sew db's.
Wandell
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Wandell 3/21/2014 1:12pm
3/21/2014 1:12pm
I actually thought about that but wasn't sure if a 90 degree or 45 degree would be best.
markit
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markit 3/22/2014 5:53am
3/22/2014 5:53am
I don't think a 45 will do much, I need to take my own advice and do this.LOL I have never been a fan of loud bikes.
xnationalwrench 3/22/2014 8:26am
3/22/2014 8:26am
Wandell wrote:
Yep, first thing I did was repack the OEM silencers and install them. I've been reading a lot about lining the airbox with foam. Will that...
Yep, first thing I did was repack the OEM silencers and install them. I've been reading a lot about lining the airbox with foam. Will that really cut down the noise a noticeable amount?
Xnationalwrench, I know you have a lot of knowledge about MX bikes. What I'm looking for is something that will make a noticeable difference in the decibel level, even if it cost me a couple horsepower. Something along the lines of what the DB Dawg used to do for four strokes.
I never cared about quiet more interested in horsepower. But the spark arrestor would quiet it down and foam in the air box would quiet the intake noise. I know that some snow mobiles and jet skis not to mention road racers use a wrap on the exhaust also.

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